A mobile station may communicate with a first radio network, such as a wireless wide area network (“WWAN”) or other radio network. The mobile station may communicate with other devices on the first radio network. The first radio network may additionally provide connectivity to one or more other networks, such as packet data networks, thereby allowing the mobile station to also communicate with devices on these other networks.
In addition to the first radio network, the mobile station may also communicate with a second radio network, such as a wireless local area network (“WLAN”) that uses one of the various Institute of Electrical and Electronics Engineers (“IEEE”) 802.11 protocols. The mobile station may connect to the second radio network and then communicate with other devices on the second radio network. The second radio network may additionally provide connectivity to other networks, such as packet data networks. The mobile station may then also communicate with devices on these other networks.
The mobile station may communicate with one or both of the radio networks, which can provide the mobile station with voice, data or other services. Although both radio networks may provide the mobile station with one or more of these services, it may still be preferable for the mobile station to communicate with one of these radio networks over the other radio network. For example, the second radio network may provide the mobile station with higher data speeds or lower access charges. Thus, given a choice between the two radio networks, it may be preferable for the mobile station to communicate with one radio network over the other network. Therefore, even when the mobile station is communicating with the first radio network, the mobile station may still want to determine the availability of the second radio network so that the mobile station can begin communicating with the second radio network when it is available.
Current methods for detecting the availability of a radio network have various limitations. In one method of detecting the availability of a radio network, a user of the mobile station manually prompts the mobile station to check the availability of the radio network. For example, in response to a command from the user, the mobile station may check for the availability of the radio network. This can disadvantageously create a delay in detecting the availability of the radio network, because while the mobile station may be within range of the radio network, the mobile station would only detect the radio network in response to a command from the user prompting the mobile station to check for the radio network. A delay in making the request would cause a delay in detecting the radio network's availability, and if the user doesn't even make a request, then the mobile station would not ever detect the radio network's availability and may lose existing radio network connectivity.
In another method of detecting the availability of the radio network, the mobile station may automatically check for the availability of the radio network, such as at predetermined time intervals. The mobile station may include, for example, a radio or other transceiver that the mobile station uses to communicate with the radio network. In order to check for the availability of the radio network, the mobile station may power-up the radio and then use the radio to attempt to communicate with the radio network. If the radio network is not available, the mobile station may power-down the radio until the next predetermined interval when the mobile station again checks for the availability of the radio network. However, powering-up and powering-down the radio in the mobile station in this manner consumes battery power, which can be undesirable for battery-powered mobile stations. Similarly, continually leaving the radio rather than periodically powering it up and down may also consume battery power and therefore be undesirable.
Therefore, there exists a need for other methods for determining the availability of a radio network.